Problem: Simplify the expression. $ (-3a^{7}-7a^{5}-5a^{4}) - ( -2a^{7}-a^{6}) $
Answer: Distribute any negative signs. $(-3a^{7}-7a^{5}-5a^{4}) + (2a^{7}+a^{6})$ Since we are adding polynomials, we can simply remove the parentheses. $-3a^{7}-7a^{5}-5a^{4} + 2a^{7}+a^{6}$ Identify like terms. $ - {3 a^7} - {7 a^5} - \color{#9D38BD}{5 a^4} + {2 a^7} + \color{#DF0030}{ a^6} $ Combine like terms. $ { ( -3 + 2 ) a^7} + \color{#DF0030}{ a^6} + { -7 a^5} + \color{#9D38BD}{ -5 a^4} $ Add the coefficients. $-a^{7}+a^{6}-7a^{5}-5a^{4}$